Climate change is bringing new challenges to communities around the world. These include nearly three billion people worldwide who depend on solid fuels for household cooking and heating.[i] In Africa, the proportion of residents dependent on solid fuels is increasing and is almost 80%. In Southeast Asia, 61% of the population still utilize solid fuels. More than a third of the people in the Eastern Mediterranean also use solid fuel—primarily wood and charcoal. Social unrest and natural disasters can lead to years long power outages that force everyone back to the basics of fuel wood and charcoal.[ii] With permanent reconstruction of the devastated power grid of Puerto Rico still pending seven years after hurricane damage, outages have become longer and more recurrent in recent years.[iii]
Lessons from the past can help improve energy and resource management today and for the future. The ancient Nabataeans used a wide range of energy resources. Their expertise enabled the capital city of Petra to prosper and support as many as 30,000 people two thousand years ago. Much can be learned from their energy management. While some studies of energy use at that time in Rome and Pompeii have been done, the analysis of energy use in the provinces away from Rome has lagged.[iv]
The energy needs of the Nabataeans were met with a wide range of resources and this diversity provided resilience in the face of climate variability and social change. The primary energy resources were biofuels with no net impact on climate change gases. Their complex energy system provided some protection against scarcity caused by drought, locusts, wildfire, war or disease. The primary energy sources included fuelwood, shrubwood and prunings, olive oil, olive pomace, grape vine prunings, charcoal, dung, food and fodder.
Many of these biofuels are little-studied and not widely understood or promoted today. A better understanding of these resources can help families and communities in Ethiopia, Sudan, Syria, Mali, Mexico, Lebanon, India, Nigeria, Chile, Laos and many other countries and regions where people still rely on these fuels.[v] The Nabataean’s expertise can be of use for many today to more sustainably manage energy while restoring forests and shrub lands.[vi]
Fuelwood
Wood was one of the most important sources of energy for the households, visitors, and businesses in Nabatea. The gross caloric potential of fuelwood is around 20 GigaJoules per ton of dry wood[vii] (a gigajoule is about equal to 26 liters of gasoline or 277 kilowatt hours). Nabatean fuel woods included oak, pistachio, juniper, hawthorne and other trees. The Nabataean demand for fuelwood and timber eventually eliminated most of the Jordanian forests. Repeated cutting with resprouting (coppicing) can work if the harvest is not too severe or repeated too often. Oaks (Quercus sp.) (baluwt) were preferred fuel wood and also provide food.[viii] Acorns are still harvested and eaten in many places including Portugal, the American Southwest, and Korea.[ix]
We don’t know for certain how much fuelwood they used, but we can look at comparable areas where fuel wood was the primary energy source. A study in the American Southwest found annual fuelwood consumption in Cochise County, Arizona in the late 1800s was about 2 cubic meters or 1.5 tons per capita.[x],[xi] Detailed studies of the potential fuelwood harvest from a comparable blue oak woodlands in California found it could provide about 10 tons of fuelwood per hectare.[xii] Thousands of hectares would have been cut every year to support the Nabatean capital and towns. Making charcoal at 10-20% efficiency would consume even more trees.
Camels or donkeys could bring fuelwood from sources far from town. A camel could carry 200 kg, a mule 150, and a donkey 25-50. Carts may also have been used on the high road Via Nova Traiana. People would carry fuelwood in as well. The forests would have gotten smaller and more barren year by year If we could go back in time, we would likely see ‘wood’ roads reaching out from Petra. As a resident of Tombstone, Arizona, noted in the late 1800s, “There were wood roads fanning out from Tombstone like the veins of a leaf, some were just tracks, others well worn.”[xiii] When the demand for fuelwood is very high the roots of trees and shrubs are dug up and burned.[xiv] Roots can be good fuelwood but their removal eliminates the possibility of resprouts and increases the risk of erosion, floods and landslides. As fuelwood costs rose, the use of prunings, pomace, dung, and imported fuels would have intensified.
Looking at the highlands and mountains of Jordan today it is hard to imagine the forests of pistachio, juniper, oak, cypress and other drought-tolerant trees and shrubs that once graced the hillsides and wadis.[xv]. The forests and woodlands have been severely reduced by human activity.[xvi],[xvii] But they can and should be restored.[xviii]
Shrub Wood and Pruning
Some shrub species were much better fuels than others and were also over-harvested. The nitrogen fixing Retama raetam has been a highly desirable fuel for cooking and heating from ancient times. Retam shrubs could provide 2-15 kg of wood each.[xix] If a household relied on shrub wood they might use 10 kg of shrubs from a hectare every month.[xx] The capital city of Petra alone might have used 4,000 ha of shrubs a year. Retam was also favored because it was not grazed heavily, but would be eaten by camels. Artemisia sieberi (sheeh) is still stockpiled in some areas for cooking fuel.[xxi] Research has made it clear that restoring healthy shrub lands is possible with water harvesting and grazing management. Within five years after planting there can be a considerable harvest every year. Multipurpose species are preferred. They can provide fuel, food, fodder and medicine.
Olive trees and other fruit and nut trees in the Nabataean agroforestry system were pruned regularly. The heating value of olive pruning debris ranged from 16.7 GJ/ton to 19.8 GJ/ton.[xxii] Olive orchards will yield 1-4 tons of olive pruning per hectare or about 50 GJ ha. However, soil health will decline if most of the organic matter is removed every year.
Nabataean wine was traded overseas and achieved a formidable international reputation. The Oxyrhynchus Papyri, dated around 280 CE, contains a contract for labor in a vineyard.[xxiii] Grapevines are pruned to improve yield and quality. The energy content of grapevine prunings ranges from to 7-18 GJ/ton. The fuel quality depends on the cultivar, the season, and management. The basket method (kouloura) of pruning is ideally suited to arid, windy sites, and might have been used.[xxiv],[xxv] Pruning might amount to 1.4-1.8 tons per hectare[xxvi] for perhaps 19 GJ/ha. Vine prunings are still used for heating and as fuel in bakery and restaurant ovens.[xxvii] Vine prunings are the preferred fuel for piglet roaster restaurants in the Bairrada region of Portugal.[xxviii]
Olive oil, Olive Pressing Waste (pomace, Jift)
Olives were an essential resource in Nabatea and olive presses have been found at almost all agricultural production sites in Jordan.[xxix] Thirty-one presses[xxx] were identified in the Brown University Petra Archeological Project.[xxxi] An ancient receipt from Umm al-Biyara and abundant traces of Nabataean agroforestry suggest the main commodity being produced was not grain but olives. Olive trees were planted on slopes and terraces as well as in more favorable locations. Olive trees were also grown within the towns and cities.[xxxii] Wild subtypes of olives (Olea europaea subsp. oleaster) are still found in the area.[xxxiii]
The olives were collected, crushed, and pressed to release the oil.[xxxiv] Olive oil has an energy content of 39 GJ/ton.[xxxv] The old, traditional olive production system in dry-farmed areas around the Mediterranean uses tree spacing from 7.6–18.3 meters apart with 30–173 trees/ha.[xxxvi] Olive yields were between 1.1–4.5 t/ha with a long delay before full production (15–40 years) and significant changes in yield due to alternate bearing.
On average 100 kg of olives will produce 14-20 kg of oil. Each 1,000 kg of olives brought in to a mill may also result in 500 kg of olive pomace (jift).[xxxvii] The amount and the oil content of the jift depend on the growing season, ripeness, cultivar, crushing method and type of press. Jift is well suited for heating and cooking as well as firing pottery and lime kilns.[xxxviii] The caloric value of jift runs from 17-24 GJ/ton.[xxxix] Olive pits also burn well with 19 GJ/ton.[xl]
Traditional rain-fed olive plantations could yield 3.5-7 tons of jift per hectare each year. Olive orchards would provide jift for use at homes, bakeries, potteries, and lime-makers. Replanting the olive groves with water harvesting should be possible. In other countries native multipurpose trees with fruits, nuts, pollen and nectar for bees, and other resources can be substituted.
Charcoal
Charcoal was used for cooking, heating water and coffee, space heating, metalwork, and smelting in Nabatea. Charcoal was expensive and this limited its use in pottery kilns. But olive pits were used as a fuel and were found in the Zurrabah kiln excavations.[xli] Charcoal would have been made in both pits and mounds. Oak was preferred, but other species and most small shrubs and prunings could be used. A ton of branches or shrubs could yield as much as 150 to 250 kg of charcoal.[xlii]
Charcoal vendors probably imported significant amounts of charcoal to the capital city, but competition for charcoal by the copper mining and smelting area of Feinan may have kept the price high . Like Rome, charcoal and wood would have been taken to a central market in Petra and sold, first by wholesalers to retailers who could afford to buy relatively large quantities, and then to individual householders, who could not. Records show that in 301 CE Rome the wholesale cost of a mule load of 140 kg of firewood was the same as a retail bundle of just 7 kg.[xliii] A profitable return!
The Bedou ‘Ammareen (sub-clan of al-Sa’idiyeen) of the Petra region were known in the nineteenth century for their charcoal trade with Egypt.[xliv] Charcoal could provide a small source of cash for individuals as well. One of EA’s friend’s grandfather would chop down a Pistacia atlantica while traveling, make charcoal, then trade it and wild game for soap, tea, sugar, and other household goods in Nablus (350 km away). Charcoal production undoubtedly contributed to the deforestation across Nabatea. Charcoal has received more attention than other biofuels, but much more could be done.[xlv]
Dung
Animal dung has been used for heating, cooking, and firing pottery in many areas of the world.[xlvi] Camels played an essential role for most of the Nabatean era.[xlvii] A camel will produce about 8 kg per day.[xlviii] It is dry and odorless and has an energy value of 12-14 GJ/ton.[xlix] Camels were essential in the spice trade caravans and a caravan might have hundreds or even thousands of camels. Camels were also bred and trained for war and the Nabatean cavalry may have had thousands of camels in service. These numbers were not matched again until WWI when the Imperial Camel Corps had 20,000 camels.[l]
Donkey dung is also fairly dry and odorless. Sheep, goats and oxen dung are also useful fuels when dried. In preparation for cooking bread or meals an oven, even today, may be heated overnight with slabs of sheep dung set around the exterior. In some areas women would store large supplies of this sheep dung.
Animal dung can be used to fire pottery without kilns in a process called bon-firing (aka clamp firing, raku). Sheep dung has been used this way by ancient and modern potters in the American Southwest.[li] Pots fired in the domestic hearth may leave no trace.[lii] Potters in villages in northern Jordan still make pottery this way.[liii] Bon-firing temperatures in a range of studies have reached between 600-900°C.[liv] Dung would also be in demand as a fertilizer for gardens and crops and burning much of the dung would eventually result in diminished soil fertility and crop yields.
Food for people
The agroforestry system developed in Nabatea was a complex mix of olives, grape vines, fruits, vegetables and grains.[lv] Wheat cultivars and barley were the important grains. The yield of emmer wheat might have been 1-3 tons per hectare. The city of Petra needed 15 tons of wheat a day and 5,000 tons a year. Grain imports probably came from the Negev highlands or even further away. Studies suggest the total area of agricultural fields in the Central Negev Highlands may well have been more than 4,000 ha.[lvi] Harvests over hundreds of years with little return of micronutrients to the soil no doubt led to lower yield and less nutritious crops.[lvii] The water harvesting techniques they developed and used to grow crops in the desert are needed around the world.[lviii]
Fodder for Animals
Most of the energy demand for the animals in Nabatea was met by open grazing. Grains might be fed at times. The soils around towns and cities were quickly laid bare by intensive grazing but highly mobile herds could seek out the best pasture even many kilometers from towns. Edible shrubs and tree seedlings would gradually disappear. Browse lines would be clear on shrubs and trees.
Overview: How Nabatean energy demand was met
Household uses: Fuelwood, shrub wood, charcoal, pomace, pruning, dung, solar energy, olive oil, etc.
Bread and Bakery: Fuelwood, shrub wood, pomace, pruning, dung
Cooking and lighting: Fuelwood, shrub wood, charcoal, pomace, olive oil
Heating and hypocaust heating: Fuelwood, charcoal, pomace
Pottery: pomace, olive pits, pruning
Smelting: Charcoal from fuelwood and shrub wood
Food for animals: Browse and feed
Food for people: Wheat, barley and other foods
Olive oil for food and lighting
Burning these fuels in the confined wadis, towns and capital would have led to significant air pollution problems. On a still day in winter it would have been very smoky. This would have adverse health impacts.
Nabataean energy use was ultimately not sustainable, but the remarkable performance of their resource management over the centuries is impressive and in many ways has never been duplicated. The take away lessons from Nabatea is to make full use of water, ’wastes’ as resources, anda wide range of species. This complexity increases resilience. Hopefully this first attempt at understanding energy use in Nabatea will lead to more detailed research providing revelations as informative as those from the engineering analysis of the water system of Petra.[lix]
Application of Nabataean soil and water management strategies could double or triple the current wheat and barley yield per hectare in Jordan. Today, Jordan produces only 100,000 tons of wheat a year with yields of just a ton per hectare.[lx] In contrast, the Nabateans used a wheat variety that may have produced 3.5 tons/ha in the Negev.[lxi] Rediscovering the Nabataean expertise could help keep some of the money now spent importing grain in Jordan in Jordan, reducing vulnerability and creating jobs. Mobile kilns and briquette makers could produce high quality charcoal from shrub wood and prunings.
Supporting rediscovery of the complex agroforestry systems developed in Petra could help olive and fruit and nut growers, vineyards, and farms prosper while improving biodiversity and providing renewable biofuels.[lxii],[lxiii] The issue of securing local energy supplies is often critical for areas and countries with limited supplies of fossil fuel. Countrywide and regional instability around the world makes local self-reliance ever more important.
The restoration of shrubs and trees can result in more local, renewable biofuels and will also sequester carbon.[lxiv] Restoration of trees, shrubs and crops will also reduce the risk from flash floods. Better control of grazing with revived use of the hima system can foster recovery of ecosystems.[lxv]
Social factors, economic pressure, tenure (land use rights), and neglect of the value of Nature’s Services have also rarely been considered. Some of the critical social aspects of ancient Petra are unknowable due to a lack of records. Obstacles to the spread and adoption of innovative systems are often complex, but not insoluble.[lxvi] Research over the last fifty years has demonstrated the feasibility of restoring damaged arid lands, but many challenges, primarily socio-cultural, remain.[lxvii],[lxviii],[lxix] Getting local communities engaged is critical.
The experts of ancient Nabatea have much to offer the World in inspiration and technique. Climate change and political instability makes action to restore lands and improve use of biofuels ever more important.[lxx]
References
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[iii]. Acevido, Nicole. “Outraged Puerto Rico residents express frustration over widespread power outages.” NBC News. June 13 (2024).
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[v] Taylor, Matthew J. 2017. Energy for the world’s kitchens: biomass for survival in the past, present, and future. pp.11-22. In: Solomon, B. and K. Calvert (eds). Handbook on the Geographies of Energy. Edward Elgar Publishing, Cheltenham, UK.
[vi] Bainbridge, David A. “Go Big! The Challenge of Large Scale Restoration of the Badiya.” EcoMENA July 18. (2024). https://www.ecomena.org/challenge-of-large-scale-restoration-of-badiya/
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[xiii]. Bahre, Conrad. A Legacy of Change. p. 152.
[xiv]. For an example in the American Southwest, see Havard, V. “The Mezquit.” American Naturalist. 18, no. 5 (1884): 451-459.
[xv]. Soga, Masashi, and Kevin J. Gaston. “Shifting Baseline Syndrome: Causes, Consequences, and Implications.” Frontiers in Ecology and the Environment 16, no. 4 (2018): 222-230.
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[xxiii]. Select Papyri, 1.18. Contract for labour in a vineyard and lease of a fruit garden.
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[xxv]. Vagelis Gavalas, 2023, personal communication. Gavalas Winery, Megalochori, Santorini, Greece.
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[xxx]. It is not always easy to tell a wine press from an oil press site.
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[xxxv]. Wikipedia, s.v. “Energy Content of Biofuel.” https://en.wikipedia.org/wiki/Biofuel#:~:text=The%20energy%20content%20in%20the,%2C%20sugarcane%2C%20or%20sweet%20sorghum.
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[xlv] Virginia Cooperative Extension. 2024. Charcoal making resources. https://ext.vt.edu/natural-resources/charcoal/charcoalmaking.html
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[lxv]. Myint, Moe, and Vanja Westerberg. “An Economic Valuation of a Large-Scale Rangeland Restoration Project through the Hima System in Jordan.” Report for the Economics of Land Degradation (ELD) Initiative by International Union for Conservation of Nature, Nairobi, Kenya, (2014).
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